Don't use afinfo.

Don't rely on afinfo to get extension name prefixes. This should make it
possible to use older versions of iptables too (e.g. 1.4.7 as reported
by several users).

Author: ldx

iptc/xtables.py

@@ -671,16 +671,6 @@ class xtables_target(ct.Union):
                 ("v10", _xtables_target_v10)]
 
 
-class xtables_afinfo(ct.Structure):
-    _fields_ = [("kmod", ct.c_char_p),
-                ("proc_exists", ct.c_char_p),
-                ("libprefix", ct.c_char_p),
-                ("family", ct.c_uint8),
-                ("ipproto", ct.c_uint8),
-                ("so_rev_match", ct.c_int),
-                ("so_rev_target", ct.c_int)]
-
-
 class XTablesError(Exception):
     """Raised when an xtables call fails for some reason."""
 
@@ -766,7 +756,10 @@ class xtables(object):
     _xtables_find_target.restype = ct.POINTER(xtables_target)
     _xtables_find_target.argtypes = [ct.c_char_p, ct.c_int]
 
-    _xtables_afinfo = ct.c_void_p.in_dll(_lib_xtables, "afinfo")
+    _xtables_set_nfproto = _lib_xtables.xtables_set_nfproto
+    _xtables_set_nfproto.restype = None
+    _xtables_set_nfproto.argtypes = [ct.c_uint8]
+
     _xtables_xt_params = ct.c_void_p.in_dll(_lib_xtables, "xt_params")
     _xtables_matches = (ct.c_void_p.in_dll(_lib_xtables, "xtables_matches"))
     _xtables_pending_matches = (ct.c_void_p.in_dll(_lib_xtables,
@@ -808,7 +801,6 @@ def _xtinit(self, proto):
         self._loaded_exts = []
 
         # make sure we're initializing with clean state
-        self._afinfo = ct.c_void_p(None).value
         self._xt_params = ct.c_void_p(None).value
         self._matches = ct.c_void_p(None).value
         self._pending_matches = ct.c_void_p(None).value
@@ -827,8 +819,6 @@ def _save_globals(self):
         # Save our per-protocol libxtables global variables, and set them to
         # NULL so that we don't interfere with other protocols.
         null = ct.c_void_p(None)
-        self._afinfo = xtables._xtables_afinfo.value
-        xtables._xtables_afinfo.value = null.value
         self._xt_params = xtables._xtables_xt_params.value
         xtables._xtables_xt_params.value = null.value
         self._matches = xtables._xtables_matches.value
@@ -843,7 +833,7 @@ def _save_globals(self):
     def _restore_globals(self):
         # Restore per-protocol libxtables global variables saved in
         # _save_globals().
-        xtables._xtables_afinfo.value = self._afinfo
+        xtables._xtables_set_nfproto(self.proto)
         xtables._xtables_xt_params.value = self._xt_params
         xtables._xtables_matches.value = self._matches
         xtables._xtables_pending_matches.value = self._pending_matches
@@ -868,8 +858,7 @@ def _get_initfn_from_lib(self, name, lib):
         try:
             initfn = getattr(lib, "libxt_%s_init" % (name))
         except AttributeError:
-            afinfo = ct.cast(self._afinfo, ct.POINTER(xtables_afinfo))
-            prefix = afinfo[0].libprefix
+            prefix = self._get_prefix()
             initfn = getattr(lib, "%s%s_init" % (prefix, name), None)
         return initfn
 
@@ -885,11 +874,18 @@ def _try_extinit(self, name, lib):
             pass
         return False
 
+    def _get_prefix(self):
+        if self.proto == NFPROTO_IPV4:
+            return "libipt_"
+        elif self.proto == NFPROTO_IPV6:
+            return "libip6t_"
+        else:
+            raise XTablesError("Unknown protocol %d" % (self.proto))
+
     def _try_register(self, name):
         if self._try_extinit(name, _lib_xtables):
             return
-        afinfo = ct.cast(self._afinfo, ct.POINTER(xtables_afinfo))
-        prefix = afinfo[0].libprefix
+        prefix = self._get_prefix()
         libs = [os.path.join(_xtables_libdir, "libxt_" + name + ".so"),
                 os.path.join(_xtables_libdir, prefix + name + ".so")]
         for lib in libs: